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RE: 2000 IBC v 1999 UBC code question

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On the topic of load combinations:

Why do we use 0.5L in some Strength design equations instead of 0.8 (IBC Eq
16-3), where f1 is 0.5 for live loads? This seems to be inconsistent.

Bill

-----Original Message-----
From: Haan, Scott M. [mailto:HaanSM(--nospam--at)ci.anchorage.ak.us]
Sent: Tuesday, October 30, 2001 7:05 AM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: 2000 IBC v 1999 UBC code question


"Using 2000 Alternate Basic Load Combination 1605.3.2 we are NO LONGER
allowed a 1/3 stress increase for wind or seismic only unless specifically
given in the material section.  This means wood only."

AISC ASD 89 A5.2 allows a 1.33 increase.
AISI Spec. A5.1.3 allows loads to be reduced.
ACI 530-99 2.1.1.1.3 allows a 1.33 increase.

"Second question, {mostly for those of you in Texas where I know that every
home is Engineered :)} where the IBC has been adopted are you still using
Simpson numbers or since they have also included a 1/3 increase on steel are
you down grading them?"

If you read in the footnotes of the "Design Table" of the specific product
you using it will indicate whether it used a 1.33 increase was used for the
tabulated value, and where to reduce for other loads.  If you are using the
alternative IBC load combinations the 1.33 increase is allowed.



Scott M Haan P.E.
Plan Review Engineer
Building Safety Division 
Development Services Department
Municipality of Anchorage
http://www.muni.org/building
phone:907-343-8183  
fax:907-249-7399
mailto:haansm(--nospam--at)ci.anchorage.ak.us



-----Original Message-----
From: George Richards P.E. [mailto:george(--nospam--at)borm.com]
Sent: Monday, October 29, 2001 9:51 AM
To: 'seaint(--nospam--at)seaint.org'
Subject: 2000 IBC v 1999 UBC code question


Fellow Engineers:

I am reviewing the impact the IBC will have on how we design out West.

Using 1997 UBC Alternate Basic Load Combination 1612.3.2 we are allowed a
1/3 stress increase for wind or seismic only loading regardless of if the
material is wood, steel, or concrete.

Using 2000 Alternate Basic Load Combination 1605.3.2 we are NO LONGER
allowed a 1/3 stress increase for wind or seismic only unless specifically
given in the material section.  This means wood only.

First question:  Did I read this correctly?

Second question, {mostly for those of you in Texas where I know that every
home is Engineered :)} where the IBC has been adopted are you still using
Simpson numbers or since they have also included a 1/3 increase on steel are
you down grading them?

Thanks in advance.

George Richards, P. E.

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